This invention relates generally to injection molding and more particularly to side gating apparatus having at least one heated nozzle which is first located laterally to allow the nozzle to be advanced for mounting of side gate seals and then located longitudinally by the side gate seals in a retracted assembled position.
As seen in U.S. Pat. No. 4,981,431 to Schmidt which issued Jan. 1, 1991, edge gating through a number of edge gate seals extending radially outwardly from a heated nozzle seated in an opening in a mold is well known. In this previous arrangement, the nozzle is located longitudinally by an insulation flange sitting on a circumferential shoulder in the mold. This was satisfactory as the cavities were located very close to the nozzles so the edge gate seals did not extend outwardly past the inner surface of the opening in the mold. This allowed the edge gate seals to be mounted on the nozzle prior to the nozzle being inserted into the opening in the mold. This is not satisfactory in applications where more space is required such as for cooling conduits extending between the heated nozzle and the surrounding cavities. In this case, longer side gate seals are required which do not fit through the opening in the mold and thus must be mounted on the nozzle after the nozzle has been inserted through the opening. The previous longitudinal location of the nozzle by the insulation flange also has the disadvantage that the longitudinal location is some distance removed from the common plane through the gates. This causes difficulty in accurate alignment of the edge gate seals with the gates due to thermal expansion and contraction. If the edge gate seals are not accurately aligned with the gates at the operating temperature, unsatisfactory reliability and quality control results.
Furthermore, in this previous arrangement the nozzle is located laterally by an outer face of each gate seal abutting against the inner surface of the opening in the mold. This has the disadvantage that the components must be manufactured to extremely close tolerances in order to provide contact at all of the edge gate seals around the nozzle and it is difficult to allow for differences in lateral thermal expansion due to different operating temperatures for different applications.